Question

why is the phospolipid layer made up of hydrophillic and hydrophobic

Answer 1

Phospholipids are amphipathic molecules. This means that they have a hydrophilic, polar phosphate head and two hydrophobic fatty acid tails. These components of thephospholipids cause them to orientate themselves, so the phosphate head can interact with water and the fatty acid tails can't, hence forming abilayer.